This invention relates generally to the heating of fluid media and materials by utilizing a resistance heating element.
For several decades, apparatuses for heating air and materials have been designed to perform in a highly efficient manner. Such designs entail consecutively wound offset spirals of resistance wire encased in a tube or flow-chamber wherein each previously wound spiral acts as a pre-heater for each of the following spirals. In most cases, this electrically charged wire is insulated by some exterior tube of refractory (hi temp) material such as ceramic or the like. These heaters work by forcing a gas, normally air, into one end of the heater and causing it to pass through a ceramic tube which supports the resistance wire and, as the air is passed over the resistance wire, it picks up energy as it transverses its way through the maze of offset spirals. This design is by far one of the most efficient and accurate methods of controlling the heating of air or gas by the use of electrical power. The drawback to this design, however, is that it provides for a very poor way to heat water or other liquids, as the electrically charged circuit is in direct contact with the media flowing over it. In most cases, liquids are not adequate candidates for such heating systems, i.e. a hair dryer in a bath tub.
Other manners of employing resistance elements for heating include heating solid materials such as metals, which possess strong temperature conductive characteristics, by way of direct contact with the solid metals. An example of such usage would be employing a resistance heater to heat metal dies.
Prior to the instant invention, contact heaters of choice for liquids, volatile gases and metals are usually those encased in some form of metal. Of course, the metals that these heaters are encased in do not perform the active heating. Rather, such metals merely act as the exchange/transfer media. A more common example of such a heating mechanism is best exemplified by the standard electric stove in a home. Within such a stove, heating on the xe2x80x9crangexe2x80x9d is accomplished by the so-called black, circular-wound coils, which are commonly referred to in the industrial community as tubular heaters. Tubular heaters are actually made of three different materials. The first and most important material is the resistance coil in the core of the xe2x80x9ctube.xe2x80x9d The next material surrounding the resistance coil is the electrical insulation, which ensures that none of the electrical energy escapes and finds an easier route for performing its intended function, which is to produce heat. This electrical insulation also performs the additional function of transferring the heat from the resistance coil to the third and final material, the encompassing steel casing. This steel casing, which is a tube itself, provides structural stability and a reasonable means of heat dissipation. By virtue of this design, this form of xe2x80x9cheaterxe2x80x9d is perfect for heating liquids because the electricity passing over the resistance coil is shielded by the layer of electrical insulation. In turn, the insulation transfers its energy to the steel casing which transfers it""s energy to the process of heating a substance. An excellent example of a tubular heater of the prior art is the IHCO PYROROD Tubular Heater disclosed in the Information Disclosure Statement submitted herewith. In view of this reference, the construction differences between the prior art and the instant invention are clearly shown.
Heretofore known products used in liquid heating and contact heating applications use tremendous electrical power and are slow and seemingly inefficient. Prior to the instant invention, in order for one to obtain a significant change in temperature in a moving liquid using a single-pass (vs. circulating) system, one was required to apply a large amount of electrical power to a system that required a significant amount of space in order to function properly.
The same problems apply to heating static, conductive materials with prior art resistance heaters. The coiled resistance wire in effect heats itself as it imparts energy to the heated material causing it to operate a higher temperature. Thus, too high a percentage of the energy generated by the coil dissipates into the surroundings, and the heater becomes extremely inefficient.
The end result of employing such an apparatus for either of the above applications was that it was bulky, inefficient, and not practical for most applications since it required too many amps.
The prior art discloses several attempts to circumvent the above-stated shortcomings. The most common of these prior art devices and methods for use in industrial application are the cartridge (depicted in the IHCO PYROWATT cartridge immersion heater), circulation (depicted in the informational brochure xe2x80x9cIntroduction to Circulation Heatersxe2x80x9d) and immersion type heaters (depicted in the IHCO PYROROD tubular immersion heater), shown and described in applicant""s Information Disclosure Statement submitted herewith. Other attempts at single pass heaters are best identified by their tradenames and marks and are known by the names of EEmax, Thermotronic, Arriston, Power Stream, SET""s and Keltech/Accutemp, all shown in more detail in the applicant""s Information Disclosure Statement.
The common deficiencies encountered with the said named products are that their efficiency ratings and durability are not as high as a wound, tubular design, as often found with air heaters. The primary shortcoming of all of these products is that they require an enormous amount of electrical service in order to make each one of these devices practically useful. Another important shortcoming of the prior art systems centers on the bulky configuration of the heating element structure.
In the above discussed prior art references, a procedure of wrapping the resistance wire into a coil was utilized to compensate for the mechanical stretching of the resistance wire inherent in the splicing or swaging process used to make the transition between conductor leads and resistance wire occurs. Other applications included a wire coil which is threaded or welded over a conductor lead or splicing mechanism. Along with creating a very bulky heating element, this coiling of the resistance wire causes great energy loss due to bunching of the wire in the swaging process. To compensate for the above-mentioned mechanical stretching, the transitional splice employed in the instant invention consists of a slide splice to join the resistance wire and conductor leads in the swaging process.
The slide splice allows for splicing a first wire possessing a first end and a second end to a second wire possessing a first end and second end. The wire splice retains the first end of the first wire and the first end of the second wire and allows axial movement of at least one the wires during the splicing process, while still maintaining the integrity of the splice and allowing current to flow.
A slide splice can simply be constructed of high-grade hypodermic nickel tubing, to a controlled depth, depending on the finished length of the heater. The motion of the wire inside the heater is compensated by the action of the slide splice. In addition to decreasing the overall outside diameter of the heater and extending the overall length of the heater, the useful function of this slide splice design is that it allows a conductor/resistance wire junction to be maintained after the physical elongation of the heater during and after the swaging process.
Before the swaging process, the end of the resistance wire is butted up against the end of the conductor lead as both are placed inside the slide splice. During the swaging process, the resistance wire tends to move axially away from the conductor lead. Due to this action, a void between the resistance wire end and conductor lead end is formed inside the slide splice. In many applications, this void would be fatal to the integrity of the resistance circuit. However, the properties inherent to the slide splice allow for the unavoidable axial motion and subsequent void development and thus allow for heater expansion, since the lengthening of the resistance wire creates a larger surface area for the heating element. This process increases the heated length of the element just as the customary coiled resistance wire does except that utilization of the slide splice allows a straight element resistance circuit to be held. Thus the slide splice provides a quick way of affixing the joint and allows room for the expansion of the wire inside the splice while still maintaining the integrity of the splice.
The instant invention therefore disposes of the above mentioned shortcomings of conventional heating elements by eliminating the need for forming the resistance wire into a coil. By compensating for elongation with the slide splice, the new invention inherently creates a more compact heating element in the process. Once the need to coil the resistance wire no longer exists, the inherent energy loss due to the wire bunching on the coil disappears. The energy supplied to the heating element can be transferred directly to the fluid or material to be heated, without having to overcome xe2x80x9chot spotsxe2x80x9d that are commonly encountered when wire bunching occurs. Thus, less electrical service is required to operate the instant system efficiently.
In much the same manner as the straight line heating element, the oval shaped heating coil eliminates xe2x80x9chot spotsxe2x80x9d created by wire bunching. Due to the longer straight wire runs on the oval shaped element, as compared with the prior art circular configurations, there exists less chance for wire bunching.
The instant invention also provides for extremely uniform and concentric heat generation as compared to the prior art coiled heaters. In a customary tubular heater, the coil has a tendency to work against itself, in that the opposite end of the exact same coil will be heating the same area of the overall heater. The superior structure of the instant invention, including a straight line heating element, disposes of this problem.
The same holds true for the oval shaped heating element as configured with the flow diverter. The longer straight runs of the oval shaped element, as compared with prior art circular heaters, working in conjunction with the fluid guiding properties of the flow diverter, allow for a more laminar flow throughout the heater and also serve to redirect fluid that would be trapped in the inner coil areas. Therefore, the coils do not get to reheat or overheat the fluids, and the areas where prior art coils tend to work against themselves are negated.
When configured to heat solid materials, the element channels much of the heat from the resistance wire that would normally work against itself to the solid much more efficiently than in standard prior art coiled resistance wire heaters. This allows for much less energy loss and thus a greater efficiency level than prior art coiled heating elements.
When utilized to heat liquids, the instant invention allows for less liquid back up and turbulent flow at the inlet of the heater than prior art heaters. The instant design inherently xe2x80x9cchokes backxe2x80x9d less liquid to the inlet walls and heating element entry area. This feature allows for a more laminar flow of liquid upon entry into the heater and thus ensures more even heat transfer and no significant energy pick up by the liquid at the inlet.
Finally, when engaged to heat solid materials, such as metal dies or plates, the instant invention offers faster more direct contact with the surface to be heated than prior art resistance heaters. The faster more direct the heat transfer, the less energy must be supplied in order to operate the system. Therefore, the instant invention provides a more cost effective alternative to heating metals.
These embodiments represent only a few of the modes in which the instant invention may be deployed and are in no way meant to restrict use the heating element to these applications. Other embodiments of the invention may be used without departing from the scope of the present invention as set forth in the appended claims.
The present invention has as its primary object the provision of an improved heating apparatus and system for heating fluid media and solid materials as well.
A more particular object of the present invention is the provision of a single-pass water heating apparatus and system having improved operational characteristics over the apparatuses and systems heretofore known and having the above noted disadvantages.
A further object of the present invention is the implementation of a more efficient system to heat solid materials, such as metal dies, which reduces heat dissipation away from the solid material and also reduces the amount of energy necessary to operate the system within the necessary parameters.
A further object of this invention is the creation of a more rugged or durable apparatus or system, which inherently possesses improved electrical efficiencies, all contained within a more compact design than that previously known or used.
Although the above features can be looked on as preferred manners of utilizing the invention, these suggestions are not meant to limit the fashion in which the instant invention may be configured or utilized. Other and further objects of the invention will be apparent from the following description and claims and may be understood by reference to the accompanying drawings, which by way of illustration, show preferred embodiments of the invention and what is now considered to be the best mode in applying principles of the invention.